M20 Pilot reported GPS; ADS-B failure which pilot believed was a problem with something other than his aircraft.

Narrative

While on personal VFR flight my aircraft ADS-B stopped transmitting over MLB when inbound for ZZZ. Was not aware of it till after landing and reviewing online aircraft tracking and saw tracking data stopped at XA:28 local time about 15 minutes prior to landing. ADS-B Out is provided via Unavonix Skybeacon wingtip strobe. During time from when ADS-B Out tracking stopped; my tablet moving map using a separate ADS-B In receiver lost GPS altitude and indicated 100 ft. GPS altitude when it was previously showing my actual indicated altitude of 5500 FT +/- 100 ft. I still had indications of other ADS-B out aircraft. I did not know my ADS-B Out was not tracking. I thought possibly bad signal to portable ADS-B in receiver or ADS-B tower down. I have utilized the portable ADS-B and tablet previously in aircraft and never had these indications before. The ADS-B Out beacon and the portable IN are separate and do not interact with each other nor does the tablet receive information from the Out beacon. I do not know if the ADS-B towers in the area went down unexpectedly or if other interference caused the OUT and IN to stop transmitting properly. As a result I was flying withing the 30 NM veil from Orlando Class B airspace requiring ADS-B out. I was not flying in or under the Class B however; but ZZZ lies within the 30 NM veil from Orlando. Since I was not on Flight Following with Orlando; I was unaware of the lost of ADS-B out data. I requested a Public ADS-B Performance Report from the FAA after seeing the Data to compare and it showed the same that my ADS-B track log stopped when flying over MLB.